Publications by authors named "I A van Rossum"

28 Publications

Deriving reference values for nerve conduction studies from existing data using mixture model clustering.

Clin Neurophysiol 2021 Aug 21;132(8):1820-1829. Epub 2021 May 21.

Department of Neurology, Leiden University Medical Center, Leiden, the Netherlands. Electronic address:

Objective: to obtain locally valid reference values (RVs) from existing nerve conduction study (NCS) data.

Methods: we used age, sex, height and limb temperature-based mixture model clustering (MMC) to identify normal and abnormal measurements on NCS data from two university hospitals. We compared MMC-derived RVs to published data; examined the effect of using different variables; validated MMC-derived RVs using independent data from 26 healthy control subjects and investigated their clinical applicability for the diagnosis of polyneuropathy.

Results: MMC-derived RVs were similar to published RVs. Clustering can be achieved using only sex and age as variables. MMC is likely to yield reliable results with fewer abnormal than normal measurements and when the total number of measurements is at least 300. Measurements from healthy controls fell within the 95% MMC-derived prediction interval in 97.4% of cases.

Conclusions: MMC can be used to obtain RVs from existing data, providing a locally valid, accurate reflection of the (ab)normality of an NCS result.

Significance: MMC can be used to generate locally valid RVs for any test for which sufficient data are available..
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August 2021

The effect of prednisolone on symptom severity in schizophrenia: A placebo-controlled, randomized controlled trial.

Schizophr Res 2021 04 10;230:79-86. Epub 2021 Mar 10.

University of Groningen, University Medical Center Groningen, Department of Biomedical Sciences of Cells & Systems, Cognitive Neurosciences, Groningen, the Netherlands.

Objective: Immune dysregulation may be involved in the pathophysiology of schizophrenia. Given the need for new treatment options in schizophrenia, anti-inflammatory medication could be a potential treatment in this illness.

Methods: In this double-blind, placebo-controlled clinical trial, patients with schizophrenia, schizoaffective disorder or psychosis NOS were randomized 1:1 to either prednisolone or placebo, in addition to their regular antipsychotic medication. Patients diagnosed with schizophrenia for less than 7 years and on antipsychotics, were treated with prednisolone or placebo, tapered-off within six weeks in the following schedule: 40 mg/day for 3 days and 30 mg/day for 4 days, followed by a decrease of 5 mg/day per week during the remaining 5 weeks. Change in symptom severity relative to baseline was compared between treatment arms, as measured through the Positive and Negative Syndrome Scale total score.

Results: In total, 68 patients signed informed consent and were screened on eligibility criteria, of whom 42 patients were randomized to either prednisolone or placebo, with 39 patients completing the treatment and tapering phase. Due to recruitment difficulties, the study was terminated prematurely. Symptom severity decreased significantly in both the prednisone and placebo treatment arm (p < 0.001). The degree of improvement was not significantly different between treatment arms (p = 0.96). No serious adverse events occurred during the treatment phase.

Discussion: There is no indication that prednisolone has a beneficial effect on symptom severity, as adjunctive treatment in patients with schizophrenia, as compared to placebo.

Conclusion: Adjunctive treatment with prednisolone did not improve symptom severity compared to placebo in patients with schizophrenia.
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April 2021

The effects of the COVID-19 outbreak and measures in patients with a pre-existing psychiatric diagnosis: A cross-sectional study.

J Affect Disord Rep 2021 Apr 1;4:100102. Epub 2021 Feb 1.

Department of Psychiatry, University Medical Center Utrecht Brain Center, Utrecht University, Heidelberglaan 100, Postal box 5500, A.01.216, Utrecht 3508 GA, the Netherlands.

Background COVID-19 has seriously affected physical and mental health world-wide,both due to spreading of the virus and due to the socially restrictive measures most governments have enforced. Increased anxiety, stress and depressive symptoms have been widely reported in the general population. The current study investigated the effects of COVID and the restrictive measures in the Netherlands on stress, anxiety and loneliness in patients with a pre-existing psychiatric disorder. Methods 189 patients with a pre-existing psychiatric disorder treated at the University Medical Center Utrecht (UMCU) provided consent to participate in an electronically provided survey. Questionnaires on anxiety, depressive symptoms, worry, stress and general health were completed by 148 participants. Results All patients reported heightened distress as well as the presence of depressive symptoms and loneliness during the initial phase of the restrictive measures. Patients could be divided into two major subgroups with either psychotic disorder ( = 71) and affective disorder ( = 86). Patients with affective disorders were more affected by the outbreak and accompanying socially restrictive measures than patients with psychotic disorders. Conclusions Our findings indicate negative mental health effects of the global COVID-19 pandemic and the restrictive measures in a particularly vulnerable population, with differential effects on diagnostic groups.
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April 2021

Study protocol of a randomized, double-blind, placebo-controlled, multi-center trial to treat antipsychotic-induced weight gain: the Metformin-Lifestyle in antipsychotic users (MELIA) trial.

BMC Psychiatry 2021 01 5;21(1). Epub 2021 Jan 5.

Department of Psychiatry, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, HP A01.126, P.O. Box 85500, 3508, Utrecht, GA, The Netherlands.

Background: Antipsychotic-induced Weight Gain (AiWG) is a debilitating and common adverse effect of antipsychotics. AiWG negatively impacts life expectancy, quality of life, treatment adherence, likelihood of developing type-2 diabetes and readmission. Treatment of AiWG is currently challenging, and there is no consensus on the optimal management strategy. In this study, we aim to evaluate the use of metformin for the treatment of AiWG by comparing metformin with placebo in those receiving treatment as usual, which includes a lifestyle intervention.

Methods: In this randomized, double-blind, multicenter, placebo-controlled, pragmatic trial with a follow-up of 52 weeks, we aim to include 256 overweight participants (Body Mass Index (BMI) > 25 kg/m) of at least 16 years of age. Patients are eligible if they have been diagnosed with schizophrenia spectrum disorder and if they have been using an antipsychotic for at least three months. Participants will be randomized with a 1:1 allocation to placebo or metformin, and will be treated for a total of 26 weeks. Metformin will be started at 500 mg b.i.d. and escalated to 1000 mg b.i.d. 2 weeks thereafter (up to a maximum of 2000 mg daily). In addition, all participants will undergo a lifestyle intervention as part of the usual treatment consisting of a combination of an exercise program and dietary consultations. The primary outcome measure is difference in body weight as a continuous trait between the two arms from treatment inception until 26 weeks of treatment, compared to baseline. Secondary outcome measures include: 1) Any element of metabolic syndrome (MetS); 2) Response, defined as ≥5% body weight loss at 26 weeks relative to treatment inception; 3) Quality of life; 4) General mental and physical health; and 5) Cost-effectiveness. Finally, we aim to assess whether genetic liability to BMI and MetS may help estimate the amount of weight reduction following initiation of metformin treatment.

Discussion: The pragmatic design of the current trial allows for a comparison of the efficacy and safety of metformin in combination with a lifestyle intervention in the treatment of AiWG, facilitating the development of guidelines on the interventions for this major health problem.

Trial Registration: This trial was registered in the Netherlands Trial Register (NTR) at as NTR NL8840 on March 8, 2020.
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January 2021

Effect of disease related biases on the subjective assessment of social functioning in Alzheimer's disease and schizophrenia patients.

J Psychiatr Res 2020 Nov 9. Epub 2020 Nov 9.

Groningen Institute for Evolutionary Life Sciences, University of Groningen, the Netherlands. Electronic address:

Background: Questionnaires are the current hallmark for quantifying social functioning in human clinical research. In this study, we compared self- and proxy-rated (caregiver and researcher) assessments of social functioning in Schizophrenia (SZ) and Alzheimer's disease (AD) patients and evaluated if the discrepancy between the two assessments is mediated by disease-related factors such as symptom severity.

Methods: We selected five items from the WHO Disability Assessment Schedule 2.0 (WHODAS) to assess social functioning in 53 AD and 61 SZ patients. Caregiver- and researcher-rated assessments of social functioning were used to calculate the discrepancies between self-rated and proxy-rated assessments. Furthermore, we used the number of communication events via smartphones to compare the questionnaire outcomes with an objective measure of social behaviour.

Results: WHODAS results revealed that both AD (p < 0.001) and SZ (p < 0.004) patients significantly overestimate their social functioning relative to the assessment of their caregivers and/or researchers. This overestimation is mediated by the severity of cognitive impairments (MMSE; p = 0.019) in AD, and negative symptoms (PANSS; p = 0.028) in SZ. Subsequently, we showed that the proxy scores correlated more strongly with the smartphone communication events of the patient when compared to the patient-rated questionnaire scores (self; p = 0.076, caregiver; p < 0.001, researcher-rated; p = 0.046).

Conclusion: Here we show that the observed overestimation of WHODAS social functioning scores in AD and SZ patients is partly driven by disease-related biases such as cognitive impairments and negative symptoms, respectively. Therefore, we postulate the development and implementation of objective measures of social functioning that may be less susceptible to such biases.
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November 2020